In the completion of oil wells which traverse earth formations, a drilled borehole is lined with one or more strings of pipe called "liners" where each liner is cemented in place with respect to the borehole by an annulus of cement. To cement the liner in the borehole the liner or string of pipe is lowered into the drilled open borehole by means of a liner hanger setting tool and string of pipe used to lower the liner hanger to the position in a casing or liner where the liner hanger is set. The liner hanger is typically set at the lower end of a string of casing or another liner and extends a liner through an open borehole where the liner extends to a location near the bottom of the open borehole. At the open end of the string of pipe is a float shoe and typically two or three pipe joints above the cementing shoe is a float collar which contains a back pressure valve. The float collar typically is a short sub with precision machined threads at each end for coupling in a string of pipe and the collar has a configured interior wall surface which receives a drillable inserted assembly which has a one way check valve. Above the float valve is a landing collar which has a bore section sized to sealingly receive a wiper plug. The landing collar also has a ratchet section in another bore section to receive a locking ratchet on a wiper plug. When the wiper plug is seated in the landing collar it must hold pressure differentials in either direction.
The float collar and the landing collar are expensive items to manufacture and utilize and the present invention involves a structure which can be disposed within the end of an ordinary joint of casing or liner and mechanically actuated by a setting tool to provide a float valve and landing collar into the end of a joint of casing or liner.